I'm interested in figurative language and metonymy in particular. Sometimes it seems hard to tell if a term qualifies as a metonym or would be considered linguistically "literal." I'm especially interested in the third of these example snippets paraphrased from a news article.

The White House opposed the plan...

Washington opposed the plan...

The U.S. opposed the plan...

The White House is commonly cited as a metonym for the U.S. executive branch government. It's the type of metonym "where one thing contains another." Washington is also used this way, using a broader structure to describe U.S. government entities.

If we go even wider in scope, we get to The U.S. Does "The U.S." qualify as a metonym in this context? It seems to function like one, but references to certain aspects of a country by using the country's name seem so common that it sounds odd to think of that as figurative language.

BONUS: If "The U.S." is a metonym in this case, where is the boundary for a country's name being figurative vs. literal?

"A refugee lives in the US," -- literal.
"A refugee went to the US." -- literal.
"The US took in a refugee" -- metonym or literal?
"The US sent back a refugee" -- metonym?

It seems literal uses of a country's name are mostly limited to referring to its geography. Is that true, or are there other rules or cases?